However, the packaging means illustrated in FIGS. 11 to 14 are not novel because they are disclosed in U.S. Pat. No. 3,973,372, U.S. Pat. No. 4,144,697, U.S. Pat. No. 4,483,125, and U.S. Pat. No. 4,571,927. The packaging apparatus described in any of these publications includes a supply conveyor centrally disposed for transporting thereon articles to be packaged, and a pair of chain conveyors disposed on both sides of the supply conveyor for transporting a film material while supporting opposite edge portions thereof. A multiplicity of articles to be packaged are transported at equispaced intervals on the supply conveyor, and the film is transported at same speed as the articles while it is supported at its opposite edge portions by the chain conveyors, so that the film is successively placed over the articles. In this connection it is noted that the chain conveyors have a downward slope extending along the path of travel of the individual articles so that the film is fed so as to gradually go into contact with the articles from an oblique direction; therefore, the film is placed from above over the articles and simultaneously stretched laterally. Beyond the chain conveyors and along the path of travel of the articles being packaged there are provided a pair of side belts for transporting the articles by holding them therebetween. Beyond the supply conveyor there is disposed a device for folding both side edge portions of the film to the underside of the articles as the film is released from the chain conveyors. Therefore, the film is wrapped in a tube form around the articles. At a further downstream location in the path of travel of the articles, the tube-form film is cut by a cutting device between each two adjacent ones of the articles. Under the path of travel of the articles carried between the side belts, there are provided air suction channels, by which the cut ends of the film are pulled downward. Each two cut ends of the film are folded to the underside of the corresponding article by both the force of movement of the article and the action of a rod-like element which runs at a greater speed than that of the article. The two film ends so folded to the underside of the article are thermowelded to the film tube in which the article is enclosed as the article is transferred on a heated belt conveyor.
Aforesaid known packaging apparatuses were developed with a view to enabling the packaging of articles to be performed with the effect of clearness by covering the articles with a stretchable film sheet while stretching the film sheet by mechanical force, then removing wrinkles present on the film. However, it has been found possible to provide the effect of film clearness by packaging articles with a heat-shrinkable film sheet while subjecting the film to shrinkage by heating. On the basis of this finding the present inventor made attempts to use both a stretchable film material and a heat-shrinkable film material with such known packaging apparatus. However, since a heat-shrinkable film material is substantially less stretchable, needs have arisen for improvement of such packaging apparatus for enabling the use with it of said two types of film materials having different properties.